mineral
Agate
Chalcedony (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7; Color: banded or multicolored (often reddish-brown with white quartz/chalcedony centers); Luster: waxy to vitreous; Crystal structure: cryptocrystalline; Cleavage: none; Specific gravity: 2.58-2.64.
- Hardness
- 6
- Luster
- waxy to vitreous
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Physical properties
Hardness: 6.5-7; Color: banded or multicolored (often reddish-brown with white quartz/chalcedony centers); Luster: waxy to vitreous; Crystal structure: cryptocrystalline; Cleavage: none; Specific gravity: 2.58-2.64.
Formation & geological history
Forms in cavities of eruptive rocks or ancient lavas from silica-rich groundwater over thousands to millions of years.
Uses & applications
Commonly used in lapidary arts, jewelry, and tumbling for collectors.
Geological facts
Lake Superior agates are famous for their rich red, orange, and yellow banding, caused by iron oxidation.
Field identification & locations
Identify by its waxy luster, translucency (especially on edges), conchoidal fracture, and often banded appearance. Look in gravel pits, riverbeds, and beaches.
